Analysis Of Hydration Kinetics And Prediction Of Elastic Properties Of Cement Based On A Micromechanical Model

Cementitious material is an important kind of structural materials for civil and industrial engineering. Its mechanical properties depend mainly on hydration process.The hydration process and evolution of the microstructures of cement are complicated. Based on a microscopic three-dimensional model for cement hydration, the thesis proposes the relation between hydration degree a and hydration radius R regarding the minimum water-cement ratio. Given the density and the composition of clinker, the relation of hydration degree a and hydration radius R can be deduced in different water-cement ratio.Based on the microscopic three-dimensional model, the thesis makes dynamic analysis of the relation between hydration radius R and time T. The hydration degree is mainly controlled by chemical reaction or diffusion rate in hydrate process. According to evolution of characteristic parameters in two main processes, the hydrated kinetic equations are given in this paper. The kinetic equations can be used to emphasize the understanding of hydration mechanism. Chemical reaction dominates in the early stage of hydration, else diffusion dose as the hydration degree increases.As Cementitious material is a typical composition, its macro-mechanical properties rely strongly on the microstructures, and can be obtained by means of mean-field theory. The multistep micromechanics approach is taken to simulate the elastic properties of cement paste, cement mortar and concrete at different hydration degree. The elastic modulus of cementitious material increases as the hydration degree increases. According to the relation of hydration degree a and time T, the evolution of elastic modulus of concrete with time can be predicted.